Multi-phase clock calibration in a receiver

A receiver, comprising:

• a front-end coupled to a transmission line to receive a signal;
• decision circuits coupled to the front-end, the decision circuits configured to compare the signal to reference voltages at times based on clocks having different phases;
• a first circuit, coupled to the decision circuits, configured to:
• receive an output of the decision circuits;
• generate, in response to the output, the reference voltages, the reference voltages being shifted from centers of data eyes at the decision circuits;
• and
• generate a control signal in response to comparisons of the reference voltages;
• and
• a second circuit, coupled to the first circuit and the decision circuits, configured to output the clocks to the decision circuits and apply at least one correction in duty cycle to at least one of the clocks in response to the control signal received from the first circuit.

A method of calibration in a receiver, comprising:

• receiving a signal;
• comparing, using decision circuits of the receiver, the signal to reference voltages at times based on clocks having different phases;
• receiving an output of the decision circuits;
• generating, in response to the output, the reference voltages, the reference voltages being shifted from centers of data eyes at the decision circuits;
• generating a control signal in response to comparisons of the reference voltages;
• and
• applying at least one correction in duty cycle to at least one of the clocks in response to the control signal.